The 2.2.1 version of nRF Connect for Mac was available to download on the developer's website when we last checked. We cannot confirm if there is a free download of this app available. The program relates to System Tools. This free Mac application is a product of Nordic Semiconductor ASA. We recommend checking the downloaded files with any free antivirus.
From the developer:
nRF Connect is a cross-platform tool that enables testing and development with Bluetooth low energy (previously called Bluetooth Smart). The tool allows for an easy setup of connections with other devices. You can use these connections for reading and writing to the external nodes.
nRF Connect is designed to be used in conjunction with the nRF51 DK, the nRF51 Dongle, or the nRF52 DK running a specific connectivity application.
You may want to check out more Mac applications, such as nrf-ble-sniffer-osx, Who Is Connected or Desktop Connect, which might be related to nRF Connect.